As known, the “push-to-talk” facility allows a group of users to be in communication one with the others through a channel. Typically, each user of the group has a terminal which is adapted to transmit and receive voice signals along the channel. Typically, each terminal is configured in a default state, wherein it can only receive voice signals from the channel. Further, each terminal is provided with a “talk button”.
When a user of the group wishes to speak, he pushes the talk button of his terminal. When the talk button is pushed, the terminal switches from the default state to a further state, wherein the terminal can only transmit voice signals along the channel (talk grant). Therefore, the user can speak while keeping the talk button pushed. Voice signals generated by the user are then transmitted over the channel to all the other users of the group. These users can only listen, until the speaking user stops speaking and releases the talk button of his terminal. In other words, the channel is managed in half-duplex mode.
While the “push-to-talk” facility allows users to receive voice signals, other facilities are known for allowing a group of users of a communication network to receive other contents, e.g. video, text or a combination thereof. In the following description and in the claims, the expression “push-to-talk” (or, briefly, PTT) will refer to a facility allowing a group of users of a communication network to be connected by means of a channel managed in half-duplex mode, independently of the type of contents (voice, video, multimedia, text, data etc.) transported by the channel. Similarly, in the following description and in the claims, the expression “talk grant” will generally refer to the right of providing content of whatever form (voice, video, multimedia, text, data, etc.).
For instance, the “push-to-talk over cellular” (or briefly POC) service allows to activate and manage push-to-talk sessions between users of a mobile telephone network, which comprises e.g. a GSM network and/or a UMTS network. A telephone network supporting the POC service typically cooperates with a POC server. The POC server manages groups of users wishing to communicate through the POC service. For interacting with the POC server, terminals must be provided with a POC client and a talk button.
When a user of a group wishes to speak, he pushes the talk button of his terminal, so that his terminal sends a talk request message to the POC server. The POC server checks whether the talk grant has already been assigned to another user of the same group. In the affirmative, the POC server refuses the request by sending a talk deny message to the user. In the negative, the POC server accepts the request by sending a talk grant message to the user. When the speaking user stops speaking, he stops keeping the talk button pushed, so that his terminal sends a talk release message to the POC server. Then, the POC server can serve talk requests from other users of the group.
In the art, it is known how to use push-to-talk (PTT) for providing contents (typically audio and/or video contents) to a group of users of a communication network.
WO 2004/086715 describes a method for distributing Push-To-Talk (PTT) voice and multimedia messages to communities of subscribers. First, a PTT group of subscribers is created in an application server. Then, the subscribers register their interest in receiving PTT messages related to the created group. Finally, a content provider server sends a PTT message destined to the PTT group, the message comprising voice and/or multimedia information. The message is received by the application server, which distributes it to the registered subscribers of the PTT group using its definition of the PTT group.
EP 1613105 discloses a system providing a push-to-talk communications facility to a group of user equipment via an access network, the system comprising a push-to-talk server and an application server. The push-to-talk server includes a controller component and a media mixer component. The controller component is operable to receive and to send control messages to and from the user equipment to establish a push-to-talk communications channel. The media mixer component is operable to receive a push-to-talk message from one member of the group and to communicate the push-to-talk message to the other members of the group via the push-to-talk communications channel. The application server is operable to provide data representing content for communication to the group of user equipment. The push-to-talk server includes a data interface for receiving the content data from the application server and a control message generator, which is operable to generate control messages. The control messages establish a push-to-talk communications channel for communicating the content data from the data interface to the group of user equipment.
In the following description and in the claims, the expression “content delivery service” will indicate a service according to which a user subscribing the service and a service provider interact by exchanging contents, such as for instance audio and/or video contents. Indeed, contents are exchanged between a terminal of the user and a network apparatus of the service provider.
In the following description, the expression “push mode” will indicate a first mode according to which a service provider and a user exchange contents. According to the push mode, the service provider delivers to the user specific contents of a given type, as soon as such contents become available. Typically, content delivery is performed after the user has declared to be interested in receiving contents of that type. An exemplary service based on push mode is a service wherein a user declares to be interested in receiving real-time news relating to a predetermined event, such as news relative to goals during a football match. During the football match, in case a goal is scored, the service provider will deliver the user a piece of news relative to the goal.
Further, in the following description, the expression “pull mode” will indicate a second mode according to which a service provider and a user exchange contents. According to the pull mode, the user asks the service provider to receive a specific content. The service provider answers to the user by sending to him the specific requested content. An exemplary service based on pull mode is web browsing. When web browsing, a user requests a specific web page to a network server hosting the web page. The network server answers to the user request by sending to the user terminal data for displaying the web page.
Further, in the following description, the expression “content providing mode” will indicate a third mode according to which a service provider and a user exchange contents. According to the content providing mode, the user delivers a specific content to the service provider. Upon reception of the content, the service provider may verify content reliability and/or correctness, and then it can provide such a content to other users. An exemplary service based on content providing mode is a traffic report service wherein users can contribute to traffic reports by sending news relative to traffic to the service provider. Upon reception of a piece of news from a user, the service provider may verify its correctness and then it can insert it into a traffic report to be transmitted to other users.